The reaction of the unsaturated nido-rhodathiaborane [8,8-(PPh3)(2)-8,7-RhSB9H10] (1) with pyridine (py) generates the new nido-hydridorhodathiaborane [8,8,8-(PPh3)(H)-9-(py)-8,7-RhSB9H9] (2) that reacts with excess ethane to give ethane and the novel ethene-ligated closo cluster [1,1-(PPh3)(eta 2-C2H4)-3-(py)-1,2-RhSB9H8] (3). Reduction of 3 with dihydrogen regenerates 2, leading to a reaction cycle that opens new routes for potential catalytic hydrogenation of olefins.